The Apple II Plus, released in 1979, is the second in the line of the Apple II series of computers. It's price at launch was $1195.

The II Plus was based on the 6502 CPU, the same CPU used in the atari 8-bit and some of the commodore 8-bit computers. The II Plus was shipped with up to 48KByte of RAM.

A special Language Card was used to bank-switch out the built-in ROM giving the computer the ability to use alternative programming languages like Apple Pascal, Fortran 77 and others. Without the language card the machine used Applesoft BASIC. The II Plus was shipped with a language-card that just contained RAM to increase the RAM capacity to 64KByte.

Shoftly after launch, Microsoft produced a Z-80 based soft-card for the Apple II computers, that allowed the machines to run CP/M. The card had circuitry to adapt the Apple Bus to be used by the on-card Z80 CPU.

The 6502 is an 8-bit MicroProcessor designed by MOS Technology. The team was led by Chuck Peddle and had also worked on the Motorola 6800. The 6502 is a simplified, but faster and cheaper design than the 6800.

The 6502 was introduced in 1975 and was the cheapest microprocessor on the market. Together with the Zilog Z80, the 6502 helped start the home computer revolution of the 1980s. The 6502 was used in a wide range of devices: the Atari 2600, the 8-bit Atari home computers, the Apple II, the Nintendo Entertainment System, the Commodore 64, the BBC Micro and many others. All used the 6502 or a variation of it.

The 6502 is a 1MHz design, while the 6502A is designed for 2MHz. The 6502A is 100% compatible with the original 6502.

Commodore soon bought MOS Technology, but conitnued to sell the microprocessor to competitors and licensed the design to other manufacturers.